Thanks for the insight!
I was going to choose the FX8120 over the 2600k because I read this from an Adobe employee: "Yes, Photoshop uses hyperthreading when it would be faster. But in many cases we can only use physical cores and not logical (hyperthreaded) cores because hyperthreading would make the process slower."
But what convinced me to go 2500k is it runs cooler, and seems to be better than any Bulldozer CPU at single-thread functions according to benches, and why this is important is because I believe (from what I have been reading) is Photoshops brush, eraser and smudge tools [ones I use the most] are still single-threaded. Manga Studio doesn't benefit from hyperthreading or multicores according to SmithMicro either.
I'm not a photographer, I only use Photoshop to paint, I don't often use filters so when I do I wouldn't mind waiting 1.3 seconds longer if it means saving some money.
I'd love to think that I could ask "Which CPU? FX6200 or 2500k" in a mature community, but no matter where I ask such things the threads end in the same way, leaving me with as little clue in which to choose as I had at the start.